If font rendering is handled by the OS for both my web browser (firefox / waterfox), and my text editor (notepad++), why do they look so much worse in the text editor? I see the same subpixel rendering in both, but the anti-aliasing seems to otherwise be worse in the editor. This has been really bothering me for a long time. See image for comparison, internet browser is on the right
edit for comment: I don't know about DPI, it's just a screenshot. OS is Windows 7. Neither side is scaled differently than the other, it's a single, cropped lossless screenshot, not two separate screenshots. (edit: NOW it's two screenshots, one on top and one underneath it.) They're both being directly rendered. With font size 10 and no zooming at all, default scale, the exact same artifacts are still there on the text editor side. Actually, that makes them far more pronounced than they are in the screenshot. I zoomed both in for the shot, intending for it to be opened and viewed at native resolution, so you could see the details more clearly. That's also why I didn't embed the image in the post, someone else did.
Anyway, I added a second shot below the first that isn't zoomed in. The same artifacts are present in both, but the two different zoom levels help demonstrate their nature. I strongly encourage anyone reading this to click them and open the files, so that they can be viewed natively. Looking at the embedded, rescaled thumbnails reveals nothing. The first shot, helps more than the second. Look at the bottom of the capital G, and the top of the lowercase l. One has antialiasing where the other seems to have practically none by comparison, other than subpixel. I do a lot of text and code editing and reading, and this has been a thing for a very long time, so it is an issue that I've always needed to fix.
edit: I just installed MacType as suggested by a commenter, and as given by their link, and thank you, it has indirectly fixed by problem. I still don't know why it rendered differently in the first place, but now that MacType overrides all rendering, it's good now. Though, the browser rendering is still better than notepad++, that of notepad++ is at least significantly improved.